Blood cell ratios show only modest links to perinatal outcomes in severe preeclampsia

Two simple blood-derived inflammatory markers, the platelet-to-lymphocyte ratio (PLR) and the neutrophil-to-platelet ratio (NPR), were linked to adverse perinatal outcomes in pregnancies complicated by severe preeclampsia, but the associations weakened substantially once maternal clinical and hematological factors were taken into account, according to a retrospective cohort study published in BMC Pregnancy and Childbirth.

The study included 524 pregnant women with severe preeclampsia. The researchers divided the patients into a group without adverse outcomes (n = 418) and a group with adverse outcomes (n = 106). The exploratory composite outcome was defined as fetal growth restriction and/or neonatal asphyxia, and the individual components were additionally analyzed as secondary outcomes.

Six inflammatory indices were compared between the two groups using the Mann-Whitney U test: the systemic immune-inflammation index (SII), the systemic inflammation response index (SIRI), the monocyte-to-lymphocyte ratio (MLR), the neutrophil-to-lymphocyte ratio (NLR), the PLR and the NPR. Women in the adverse-outcome group had a lower PLR and a higher NPR, with P values of 0.010 and 0.005, respectively.

However, these unadjusted differences did not hold up equally well under statistical adjustment. After controlling for gestational age at delivery, 24-hour urinary protein and diastolic blood pressure, PLR remained modestly associated with the composite outcome, with an adjusted odds ratio of 0.950 per 10-unit increase (95% CI 0.904–0.998, P = 0.042). NPR, by contrast, was not significantly associated after adjustment, with an adjusted odds ratio of 1.048 per 0.01-unit increase (95% CI 0.962–1.142, P = 0.286).

The researchers also ran a sensitivity model that additionally addressed platelet-related confounding. In that model, the PLR association was attenuated and no longer reached statistical significance, with an adjusted odds ratio of 0.945 per 10-unit increase (95% CI 0.891–1.003, P = 0.062).

Component-specific analyses suggested different patterns for fetal growth restriction and neonatal asphyxia, although the asphyxia analysis was limited by only 15 events, which restricts the reliability of that particular finding.

The predictive performance of the markers was also modest. In exploratory receiver operating characteristic analysis, a model combining all six inflammatory indices had an apparent area under the curve of 0.656, which decreased to 0.632 after bootstrap correction for optimism. Multivariate logistic regression and ROC curves were used to assess predictive performance across the cohort.

The authors concluded that lower PLR and higher NPR were associated with adverse perinatal outcomes in unadjusted analyses, but that these associations were substantially influenced by gestational age and maternal clinical and hematological factors. Given the modest discriminatory performance and the attenuation of the adjusted associations, they advised interpreting PLR and NPR as exploratory markers rather than established clinical predictors in severe preeclampsia.

As a retrospective single-cohort analysis, the study describes associations within the observed population and cannot establish causal relationships. The findings, published on 28 October 2026 as an open-access article, suggest that while routinely available blood count ratios may reflect inflammatory patterns in severe preeclampsia, their value for identifying pregnancies at risk of fetal growth restriction or neonatal asphyxia remains limited and requires further investigation before any clinical use.

Subject of Research: Associations of platelet-to-lymphocyte and neutrophil-to-platelet ratios with adverse perinatal outcomes in severe preeclampsia

Article Title: Associations of platelet-to-lymphocyte and neutrophil-to-platelet ratios with adverse perinatal outcomes in severe preeclampsia: a retrospective cohort study

Article References: Ju, H., Wei, R., Wang, Y., Li, Y., & Deng, X. (2026). Associations of platelet-to-lymphocyte and neutrophil-to-platelet ratios with adverse perinatal outcomes in severe preeclampsia: a retrospective cohort study. BMC Pregnancy and Childbirth. https://doi.org/10.1186/s12884-026-10155-8

Image Credits: AI Generated

DOI: 10.1186/s12884-026-10155-8

Keywords: severe preeclampsia, platelet-to-lymphocyte ratio, neutrophil-to-platelet ratio, perinatal outcomes, fetal growth restriction, neonatal asphyxia, inflammatory markers, retrospective cohort study, logistic regression, predictive performance, Associations, platelet-to-lymphocyte